#include <stdio.h>
#include <ctype.h>

int main(int argc, char **argv)
{
    char c;
    int vowels = 0;

    printf("Enter a sentence: ");

    while ((c = getchar()) != '\n')
    {
        switch (toupper(c))
        {
        case 'A':
        case 'E':
        case 'I':
        case 'O':
        case 'U':
            vowels++;
            break;
        default:
            break;
        }
    }

    printf("Your sentence contains %d vowels.\n", vowels);

    return 0;
}
